title: Influence of acute hypoxia and radiation quality on cell survival.
abstract: To measure the effect of acute oxygen depletion on cell survival for different types of radiation, experiments have been performed using Chinese hamster ovary (CHO) cells and RAT-1 rat prostate cancer cells. A special chamber has been developed to perform irradiations under different levels of oxygenation. The oxygen concentrations used were normoxia (air), hypoxia (94.5% N2, 5% CO2, 0.5% O2) and anoxia (95% N2, 5% CO2). Cells were exposed to X-rays and to C-, N- or O-ions with linear energy transfer (LET) values ranging from 100-160 keV/µm. The oxygen enhancement ratio (OER) and relative biological effectiveness (RBE) values have been calculated from the measured clonogenic survival curves. For both cell lines, the X-ray OER depended on the survival level. For particle irradiation, OER was not dependent on the survival level but decreased with increasing LET. The RBE of CHO cells under oxic conditions reached a plateau for LET values above 100 keV/µm, while it was still increasing under anoxia. In conclusion, the results demonstrated that our chamber could be used to measure radiosensitivity under intermediate hypoxia. Measurements suggest that ions heavier than carbon could be of additional advantage in the irradiation, especially of radioresistant hypoxic tumor regions.
authors.affiliation: Biophysics Department, GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Tinganelli
authors.forename: Ning-Yi
authors.initials: NY
authors.lastname: Ma
authors.forename: Cläre
authors.initials: C
authors.lastname: Von Neubeck
authors.forename: Andreas
authors.initials: A
authors.lastname: Maier
authors.forename: Corinna
authors.initials: C
authors.lastname: Schicker
authors.forename: Wilma
authors.initials: W
authors.lastname: Kraft-Weyrather
authors.forename: Marco
authors.initials: M
authors.lastname: Durante
mesh_terms: D000818:Animals; D016466:CHO Cells; D015687:Cell Hypoxia / Q000528:radiation effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000528:radiation effects*; D006224:Cricetinae; D003412:Cricetulus; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D007477:Ions / Q000627:therapeutic use; D018499:Linear Energy Transfer; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000473:pathology; D011878:Radiotherapy; D051381:Rats; D014965:X-Rays
chemical_list: D007477:Ions; D010100:Oxygen
keywords: LET; OER; hypoxia; radiosensitivity